Ultrapure polycrystalline silicon used in the electronic and solar industry is often produced through deposition from gaseous reactants via a chemical vapor deposition (CVD) process conducted within a reactor.
FIGS. 1 and 2 show an arrangement of silicon rods 100 within a CVD reactor (the reactor is omitted for clarity). Individual silicon rods 100 are coupled together in pairs by silicon bridges 102. The rods 100 are connected to a plate 104. The plate 104 of rods 100 is disposed within a housing of a CVD reactor. Each pair of coupled rods 100 has a characteristic U-shape. The rods 100 are arranged in three concentric circles. Twelve rods 100 are disposed along the inner circle, 18 rods along the middle circle and 24 rods along the outer circle, for a total of 54 rods.
One such process used to produce ultrapure polycrystalline silicon in a CVD reactor is referred to as a Siemens process. Silicon is deposited on the surface of the rods 100 in this process and the rods 100 are used as seeds to start the process. Gaseous silicon-containing reactants flow through the reactor and deposit silicon onto the surface of the rods 100. The gaseous reactants (i.e., gaseous precursors) are silane-containing compounds such as halosilanes or monosilane and are heated to temperatures above 1000° C. Under these conditions the gaseous reactants decompose on the surface of the rods 100 so that silicon is deposited according to the following overall reaction:2HSiCl3→Si+2HCl+SiCl4.
The process is stopped after a layer of silicon having a predetermined thickness has been deposited on the surface of the rods 100. The silicon rods are then harvested from the CVD reactor for further processing.
Traditional tools are designed to extract two rods 100 from the CVD reactor in one operation. This tool, commonly known as a “partner”, is lowered around one pair of rods 100 at a time and fastened to a portion of the rods. The tool is then lifted to extract the pair of rods 100 from the reactor. The rods are then removed and stored for processing.
Several drawbacks are apparent when using the traditional tool to extract the rods 100 from the CVD reactor. First, the harvesting procedure must be performed many times. For a 54 rod reactor, the procedure has to be performed 27 times, resulting in a time-consuming procedure. Second, the tool is cumbersome and difficult to operate within the narrow spans between the rods 100 and neighboring rods can be damaged during removal of adjacent rods from the reactor. Third, after the first pair of rods 100 has been extracted from the reactor, the tool is unavailable for further use until the extracted pair of rods 100 has cooled because the rods cannot be removed from the tool until they have cooled. This cooling time delays the removal of the remaining rods 100, resulting in a longer shutdown of the reactor. Lastly, it can be difficult to lower the tool along a straight-forward track around the pairs of rods 100 since it cannot be guided easily.
This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.